Table 2.

 Criteria for measuring agreement between endoanal ultrasound and magnetic resonance imaging (MRI) for the internal and external anal sphincters

Level of agreement	Criteria
Complete agreement	Normal appearance versus mild focal thinning
	Similar findings* within two hours on the clock face
	Similar findings* located at the same or within one craniocaudal level
Acceptable agreement	Marked focal thinning versus tear
	Marked focal thinning versus scar
	Atrophy alone versus atrophy with tear versus atrophy with scar
	Similar findings* separated by ⩾ one craniocaudal level
	Similar findings* separated by > 2 hours on the clock face
Disagreement	Any other combination not listed above

*For external sphincter, similar findings indicates tear or scar by MRI versus defect by ultrasound.